Summarized Consolidating Financial Data - Consolidating Income Statements (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 25, 2015	Sep. 26, 2014	Sep. 25, 2015	Sep. 26, 2014
Consolidated Income Statement
Revenue	$ 2,939	$ 3,221	$ 9,030	$ 9,477
Operating Expenses	2,006	2,245	6,237	6,765
Operating Income	933	976	2,793	2,712
Equity in Earnings of Subsidiaries	0	0	0	0
Interest (Expense) / Benefit	(136)	(137)	(404)	(412)
Nonoperating Income (Expense)	2	(26)	8	(31)
Earnings Before Income Taxes	799	813	2,397	2,269
Income Tax Benefit / (Expense)	(292)	(304)	(895)	(833)
Net Earnings	507	509	1,502	1,436
Total Comprehensive Earnings	518	518	1,523	1,476
CSX Corporation
Consolidated Income Statement
Revenue	0	0	0	0
Operating Expenses	(154)	(113)	(448)	(321)
Operating Income	154	113	448	321
Equity in Earnings of Subsidiaries	496	527	1,482	1,488
Interest (Expense) / Benefit	(134)	(133)	(399)	(389)
Nonoperating Income (Expense)	(1)	(12)	(4)	(17)
Earnings Before Income Taxes	515	495	1,527	1,403
Income Tax Benefit / (Expense)	(8)	14	(25)	33
Net Earnings	507	509	1,502	1,436
Total Comprehensive Earnings	518	518	1,523	1,476
CSX Transportation
Consolidated Income Statement
Revenue	2,920	3,202	8,972	9,417
Operating Expenses	2,182	2,368	6,765	7,121
Operating Income	738	834	2,207	2,296
Equity in Earnings of Subsidiaries	0	1	0	1
Interest (Expense) / Benefit	(8)	(11)	(24)	(39)
Nonoperating Income (Expense)	5	(9)	18	(13)
Earnings Before Income Taxes	735	815	2,201	2,245
Income Tax Benefit / (Expense)	(273)	(309)	(824)	(831)
Net Earnings	462	506	1,377	1,414
Total Comprehensive Earnings	462	507	1,374	1,422
Eliminations and Other
Consolidated Income Statement
Revenue	19	19	58	60
Operating Expenses	(22)	(10)	(80)	(35)
Operating Income	41	29	138	95
Equity in Earnings of Subsidiaries	(496)	(528)	(1,482)	(1,489)
Interest (Expense) / Benefit	6	7	19	16
Nonoperating Income (Expense)	(2)	(5)	(6)	(1)
Earnings Before Income Taxes	(451)	(497)	(1,331)	(1,379)
Income Tax Benefit / (Expense)	(11)	(9)	(46)	(35)
Net Earnings	(462)	(506)	(1,377)	(1,414)
Total Comprehensive Earnings	$ (462)	$ (507)	$ (1,374)	$ (1,422)